1819.) Royal Society. 219 
respect to the origin of languages and nations. In speaking of 
the density of the earth, Dr. Y. attempted to show that the 
general law of compression is quite sufficient to explain the greater 
density of the interior of the earth, and that this law, which is 
true for small pressures, in all substances, and universally in 
elastic fluids, requires some modification for solids and liquids, 
the resistance in them increasing faster than the density; for 
no mineral substance, he observed, is sufficiently light and in- 
compressible to afford a sphere as large as the earth, and of 
the same specific gravity, without such deviation from the gene- 
val law. A sphere of water or of air would be still more dense, 
and the moon, if she contained such cavities, would soon have 
absorbed her atmosphere, if she had ever possessed any. 
The paper concluded with some remarks on Euler’s formula 
for the rolling pendulum, in which the perfect accuracy of La- 
place’s theory, for the length of the convertible pendulum rolling 
on equal cylinders, was shown. 
Jan. 28.—A paper, by Capt. W. J. Webbe, was read, entitled 
“ Memoir of a Survey of the Province of Keemaon.” The author 
stated in this memoir, that from the difficulty of obtaining any 
thing like an accurate base by route measurement upon the plain, 
he was induced to consider how far such a base might be accu- 
rately deduced from astronomical observations. Having a good 
reflecting circle, he found that by multiplied observations near 
the meridian, the latitudes obtained on different days did not vary 
from one another more than 2” or 3”. From the difficulties, 
however, he had to encounter, he was, after all, under the neces- 
sity of adopting a proximate primary base, reserving its correction 
till a future opportunity. In determining the elevations of 
mountains, he used Mr. Colebrook’s formula. The paper con- 
cluded with an account of the heights of many of the snowy 
peaks of the ridge from which the Dnieper, Don, and Volga, 
descend on the European side, and the Ganges and Indus on the 
Asiatic; and appended was an extensive catalogue of the lati- 
tudes, longitudes, and elevations of places and stations in the 
province of Keemaon. 
At this meeting was also read, a paper, by Professor Aldini, 
entitled ‘An Experimental Inquiry upon Gas Light on the 
Continent, with some Observations upon the Present State of 
the Illumination of London.” After some general remarks, the 
author suggested, that when coals cannot be obtained, turf may 
be substituted ; also the refuse bark of tan yards, pitch, tar, 
petroleum, and oil, as now employed by Messrs. Taylor. He 
also suggested. the possibility of employmg hydrogen from the 
decomposition of water for augmenting the quantity of gas. 
Feb. 4.—A paper, by W. Baim, Esq. was read, on the dangers 
to which navigation is exposed by navigators neglecting to make 
the local attraction on shipboard an element of calculation. The 
author commenced by making remarks on Capt. Ross’s recent 
observations on the magnetic variation in the northern regions; 
